Air conditioner

ABSTRACT

An air conditioner in accordance with the invention comprises a first unit including a compressor and a heat exchanger; a second unit including a heat exchanger; a refrigerant circuit connecting the compressor and the heat exchanger of the first unit, with the heat exchanger of the second unit, through which a refrigerant flows; a refrigerant pressure reduction valve disposed in the refrigerant circuit and provided in the second unit; a control unit provided in the first unit for controlling the refrigerant pressure reduction valve in the second unit.

This application is a Continuation of application Ser. No. 08/751,791,now U.S. Pat. No. 5,689,965 filed Nov. 18, 1996, which is a continuationapplication of Ser. No. 08/170,861, filed Dec. 21, 1993.

The present invention relates to air conditioners of the separationtype.

In general, an air conditioner of the separation type comprises one unitprovided with a compressor and a heat exchanger, and another unitprovided with a heat exchanger and an refrigerant pressure reductionmeans which is located in a space to be air-conditioned. A refrigerantcircuit interconnects both units to provide a refrigeration cycle. Someof the separation type air conditioners include valve means designed toreverse a flow direction of a refrigerant in order to change overbetween space heating and space cooling. A control unit is provided tocontrol the refrigerant pressure reduction means (for example, anelectric expansion valve), so that an interior of the space ismaintained at a desired condition. For example, the one unit is locatedoutside of a dwelling and the other unit is located inside of thedwelling to serve for provide heating and cooling of a room.

In these air conditioners, a control unit is arranged inside of the another unit as disclosed JP-A-60-226667 and JP-A-3-211370. Accordingly,in the case when it is desired to replace the compressor or a wholeoutside unit (or the one unit), it is necessary to replace not only theoutside unit (the one unit) but also the inside unit (the an other unit)because a control unit is required to meet the specification of thecompressor to be replaced. However, since most of the inside units arebuilt-in or secured in being air conditioned the rooms, theirreplacements cannot easily be done.

OBJECT AND SUMMARY OF THE INVENTION

The present invention has an object to provide an air conditioner whichmakes it unnecessary to replace the inside unit (the an other unit) in acase when it is desired to replace the compressor or a whole outsideunit (the one unit).

To this end, in accordance with the present invention, there is providedan air conditioner which comprises: a first unit including a compressorand a heat exchanger; a second unit including a heat exchanger; arefrigerant circuit connecting the compressor and the heat exchanger ofthe first unit with the heat exchanger of the second unit, through whicha refrigerant flows; a refrigerant pressure reduction means disposed inthe refrigerant circuit and provided in the second unit; and a controlunit provided in the first unit for controlling the refrigerant pressurereduction means in the second unit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an air conditioner in accordance with aone embodiment of the present invention having a single inside unit; and

FIG. 2 is a diagram illustrating an air conditioner in accordance withanother embodiment of the present invention having a plurality of insideunits.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to FIG. 1, an air conditioner is provided with one outsideunit (OU) located outside of a dwelling and with one inside unit (IU)located inside of a room of the dwelling.

The outside unit (OU) comprises a compressor 1, a reversing valve 2, aheat exchanger 3 and an accumulator 6. The inside unit (IU) comprises anelectric expansion valve 4 and a heat exchanger 5. These elements areconnected together by a pipe line through which the refrigerant flows toform a refrigerating cycle.

In cooling mode, the compressor 1 compresses the refrigerant into thegaseous refrigerant of a high temperature and a high pressure. In theheat exchanger 3, the gaseous refrigerant from the compressor 1 throughthe reversing valve 2 emits the heat to the outside and then condensesinto the reduced refrigerant. The reduced refrigerant from the heatexchanger 3 adiabatically expands in the expansion valve 4 of the insideunit (IU). Further, the reduced refrigerant evaporates in the heatexchanger 5 into the gaseous refrigerant. At this point, the heat isabsorbed from the air in the room to cool the latter. The gaseousrefrigerant from the heat exchanger 5 flows via the reversing valve 2into the accumulator 6 where the liquid refrigerant is removed. Theliquid refrigerant-free gaseous refrigerant returns back to thecompressor 1.

In heating mode, the reversing valve 2 is switched over in a state shownby the broken line. The high-temperature and high pressure gaseousrefrigerant from the compressor 1 emits the heat outside in the heat tothe exchanger 5 of the inside unit (IU) and then condenses into thereduced refrigerant. At this point, the heat is transferred to the airin the room so as to heat the latter. Next, the reduced refrigerant fromthe heat exchanger 5 adiabatically expands in the expansion valve 4 ofthe inside unit (IU). Further, the reduced refrigerant evaporates in theheat exchanger 3 into the gaseous refrigerant and flows via thereversing valve 2 into the accumulator 6 where the liquid refrigerant isremoved. The liquid refrigerant-free gaseous refrigerant returns back tothe compressor 1.

In either case, an opening degree of the electric expansion valve 4 ofthe inside unit (IU) is controlled in order to achieve a desired roomtemperature. This control is effected by a control unit 7 provided inthe outside unit (OU). The control unit 7 determines an appropriateopening degree of the electric expansion valve 4 based on therefrigerant temperatures in the respective portions of the refrigerantcycle, the temperatures of the air blown out of the heat exchangers andthe operating mode demands or the like.

More specifically, with regard to the refrigerant temperature within therefrigerant cycle, a sensor 11 detects the temperature of therefrigerant flowing out of the compressor 1, a sensor 12 detects thetemperature of the refrigerant flowing out of the heat exchange 3 duringthe cooling mode, and a sensor 13 detects the temperature of therefrigerant flowing into the heat exchanger 5 during the cooling mode.As regards the temperature of the air blown out of the heat exchanger, asensor 21 detects the temperature of the air sucked into the heatexchanger 3. A sensor 22 detects the temperature of the air sucked intothe heat exchanger 5 at the cooling mode and a sensor 23 detects thetemperature of the air blown out of the heat exchanger 5 at the coolingmode. The information from an operating mode selection unit 31 and thedetected temperatures are converted into electrical signals atinterfaces 71 and 72 and these electrical signals are input into thecontrol unit 7. The control unit 7, based upon the electrical signalsfrom the interfaces 71 and 72, determines a desired opening degree ofthe electric expansion valve 4 in accordance with a predeterminedprocedure. The control unit 7 feeds a pulse train 81 having a duty ratiocorresponding to the desired opening degree of the electric expansionvalve 4 thereto, so that the opening degree of the electric expansionvalve 4 is controlled.

Further, the control unit 7, based upon the electrical signals from theinterfaces 71 and 72, feeds a command signal 82 for switching over thereversing valve 2 and a command signal 83 for altering a capacity of thecompressor 1 to the reversing valve 2 and the compressor 1,respectively, if necessary.

Next, consider the case when in a sparation-type air conditioner thewhole outside unit (OU) needs to be replaced or the compressor 1 in theoutside unit (OU) needs to be replaced. In the above-mentionedairconditioner, valves 91-94 are first closed. After replacing the wholeoutside unit (OU) or the compressor, the outside unit (OU) and theinside unit (IU) are re-connected together and the valves 91-94 areopened. This will complete a replacement. In this embodiment, since thecontrol unit 7 determines a desired opening degree of the electricexpansion valve 4 in accordance with a procedure corresponding to thenew compressor is renewed together with the outside unit (OU), therewill be no need to replace the inside unit (IU). To the contrary in aprior-art air conditioner, since the control unit is provided in theinside unit (IU), the inside unit (IU) needs to be replaced in order toreplace the control unit in case of replacing the outside unit (OU).This is a serious matter for a built-in type inside unit (IU).Specifically, the replacement of the built-in type inside unit increasesthe time and cost required to replace the whole air conditioner. Incontrast, in accordance with the present invention, the replacement ofthe inside unit (IU) is eliminated. This means that since the insideunit (IU) need not be replaced, the users can enjoy an advantage thatthe time and the cost required for replacement of an air conditioner ismarkedly reduced.

FIG. 2 illustrates another embodiment of the present invention in whichthere are provided one outside unit (OU) and a plurality of inside units(in this embodiment, three inside units IU1-IU3) in rooms on therespective floors inside of the dwelling. The outside unit (OU) and eachof the inside units (IU1 to IU3) are identical to those shown in FIG. 1,respectively. In this embodiment, the inside units (IU1 to IU3) arearranged in parallel to one another.

The temperatures detected in the respective rooms, and temperaturedetected in the outside unit (OU) and the information from the operatingmode selection units 311-313 are converted into electrical signals atthe interfaces 71 and 721-723, and these electrical signals are inputinto a control unit 70. The control unit 70, based upon the electricalsignals from the interfaces 71 and 721-723, determines the respectiveopening degrees of the electric expansion valves 41, 42 and 43. Thecontrol unit 70 feeds pulse trains 811-813 having duty ratioscorresponding to the required opening degrees of the electric expansionvalves 41-43, respectively to these valves to control the openingdegrees thereof. In this manner, the temperature of each room ismaintained as desired.

In this embodiment, in the case when it is desired to replace a wholeoutside unit (OU) or the compressor 1 of the outside unit (OU), theinside units (IU1 to IU3) do not need to be replaced with new ones sincethe control unit 70 determines the desired opening degrees of theelectric expansion valves 41-43 in accordance with a procedure requiredfor a new compressor which is replaced together with the output unit(OU). This eliminates the need for a user to replace the inside unit(IU), which lessens the time and the cost required for replacement ofair conditioner substantially. In addition, this enables a manufacturerto make inside units (IU) of the same construction for a variety ofoutside units, thus holding down the cost of production. Further, aproduct stock of the inside units can be readily managed and the insideunits can be readily made available by the distributors.

What is claimed is:
 1. An air conditioner comprising:an inside unitincluding an electric expansion valve and an interior heat exchanger;and an outside unit including a compressor and an exterior heatexchanger, wherein said outside unit further includes means fordetermining an opening degree of said expansion valve in accordance withtemperature and operation information from said inside unit, and whereinsaid air conditioner can be updated by replacing said outside unit witha new outside unit, without replacement of said inside unit.
 2. An airconditioner according to claim 1, wherein the outside unit includes acontrol device for feeding a pulse train directly to said electricexpansion valve to control the opening degree thereof.
 3. An inside unitof an air conditioner comprising an electric expansion valve and aninterior heat exchanger, wherein said inside unit feeds temperature andoperation information to an outside unit including a compressor and anexterior heat exchanger, and wherein said electric expansion valve ofsaid inside unit is controlled to an opening degree thereof directly bythe outside unit.
 4. An outside unit of an air conditioner comprising acompressor and an exterior heat exchanger, wherein said outside unitreceives temperature and operation information from an inside unitincluding an electric expansion valve and an interior heat exchanger anddetermines an opening degree of the expansion valve of the inside unitin accordance with the temperature and the operation information fromthe inside unit.